Currently there's asynchronous leaderboardy business which has been part of Trials since the first game. There's also a local multiplayer option for four people. I gave it a bash at a preview event shortly before its release in April. and although fun it had a few problems, not least that if you were at the far end of the bank of racers everyone else would be obscuring your view.
The solution when I played was that the order of the bikes on the track was randomised so you'd be unlikely to be in the back all the time. It was far from perfect, though and Antti Ilvessuo (creative director of RedLynx – the studio behind the game) says the same problem worsened when you took the game online in Fusion's predecessor, Trials Evolution.
"While this isn’t typically a problem in Local Multiplayer when you’re with friends, yelling and having fun – it didn’t translate well online, where it could feel remote and unfair," said Ilvessuo.
Instead, online multiplayer for Fusion will always have the player as the character closest to the screen. Basically, everyone will see themselves as the nearest rider, regardless of where they might appear to be on a friend's screen. The change means it's easier to keep an eye on where everyone is without sacrificing player visibility. That's also why RedLynx have been able to boost the number of players to eight instead of four.
Consoles will get a free content update with the multiplayer mode before the end of 2014 while us PC players have been promised a multiplayer beta soon.